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초록

This study proposes an integrated oxidative coupling of methane (OCM) process for the co-production of ethylene and hydrogen, aiming to overcome the limitations of conventional single-reactor OCM and improve system-level performance while addressing resource sustainability in ethylene production. The proposed processes employ a two-stage isothermal reaction system to improve methane conversion and C2 selectivity, combined with an alternative separation strategy and on-site energy recovery via combined heat and power integration. Rigorous process simulations were conducted to establish mass and energy balances, followed by comprehensive techno-economic and environmental analysis. The optimal configuration achieved an ethylene unit production cost of 0.97 USD/kg, representing a 55.9% reduction relative to a conventional single-reactor OCM benchmark (2.2 USD/kg), driven by staged conversion, elimination of methane recycles, and hydrogen coproduction. Net CO2-equivalent emissions were reduced by 66.2% to 4.50 kg CO2 per kg C2H4. Sensitivity analysis identified hydrogen value, methane price, and the methane/oxygen ratio as key determinants of economic feasibility. A multi-metric assessment incorporating energy use, carbon efficiency, feedstock availability, and price elasticity shows that methane-based direct conversion pathways exhibit favorable structural characteristics, particularly in terms of feedstock robustness. These results provide practical solutions to cost-competitively diversify resources for ethylene production, while leveraging emerging hydrogen markets.

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